In a conventional communication system, data transmission between a base station and a terminal or between a relay station and a terminal is performed in unicast, multicast, and broadcast manner. Multicast and broadcast transmissions are defined mainly in a multicast and broadcast service (MBS) region. Although various data transmission methods are defined in a non-MBS region, an efficient multicast transmission is not sufficiently defined.
A group call may be used in a communication system. For example, a group call may be preferred in a communication method of a command and control system for public protection and disaster relief. Among the transmission methods, multicast transmission may be applied to the group call. In a conventional communication system, however, there is a restriction in the use of a multicast-based group call, especially in a non-MBS region, and accordingly the definition of a multicast transmission method is required.